C-reactive protein and the risk of colorectal adenoma in CLUE II.

B187

Context: Animal models and mechanistic studies implicate inflammation as a key predisposing factor to sporadic colorectal neoplasia. In the last three years seven prospective epidemiological studies have been published evaluating the association of C-reactive protein (CRP) with colorectal cancer. Many but not all of these studies found higher CRP levels to be associated with a risk of colorectal cancer. No published studies exist on CRP and precursor colorectal adenomas. Objective: To evaluate the association of plasma CRP concentrations with risk of colorectal adenoma. Methods: Colorectal adenoma cases (n= 135) and matched controls (n=269) who had had a negative sigmoidoscopy or a colonoscopy were identified between baseline in 1989 and 2000 from among participants in the CLUE II cohort of Washington County, Maryland. Cases were confirmed by medical record review. Controls were matched with cases on age, sex, race, date of blood draw, time since last meal, and date of endoscopy. Concentrations of CRP were measured in baseline blood specimens using a high sensitivity assay. Conditional logistic regression models were used to estimate matched odds ratios. Results: Plasma CRP concentrations were similar between colorectal adenoma cases and controls (median CRP, 1.31 vs 1.38 mg/L; P = 0.71). The risk of colorectal adenoma among those in the highest fourth of CRP levels compared to the lowest fourth was 0.63 (95% confidence interval, 0.35 - 1.14; P for trend = .27). Results were similar for proximal or distal location of adenomas. Discussion: Plasma CRP concentrations were not positively associated with colorectal adenoma. More work is needed to determine whether CRP is a valid marker of intra-colonic inflammation, and whether such inflammation contributes to the etiology of sporadic colorectal neoplasia.